The present invention relates to microprocessor systems. A microprocessor system operates under micro-code control. The microprocessor system is aided by various support circuits, e.g., memory, timers and registers, to perform predetermined tasks and the microprocessor controls the support circuits through electrical connections. The logical steps executed by the microprocessor cause the support circuits to obtain particular electronic states. In the event of a microprocessor failure, the support circuits can be erroneously affected and enter an erroneous electronic state. Protection of memory elements in the support circuits is important in recovery from failures or determining the type of failure. A disadvantage of microprocessor systems is the inability to protect the electronic state of support circuits from errors caused by a failing microprocessor.